Reducing the power loss in electric loads has been a focus of much development for some time. While early work focused on power transmission losses, more recent developments have also addressed power losses in 220 volt and 110 volt residential and commercial site load networks.
Power efficiency meters connected between a utility metering device and a residential or commercial load can measure the power loss or efficiency of such a site load network. One method described to reduce power loss has been to alter the sinusoidal shape of the 60 cycle voltage supplied by a utility company. The object of such previous work was to reduce the transition time of the voltage from half peak value to half peak value. This was done with 110 volt or 220 volt power supplies connected between a utility metering device and an electric load.
For example, an energy savings device power supply having an internal dc battery is disclosed in U.S. Pat. No. 3,319,074. An external ac source is rectified and applied to a load under control of a transistor. The dc battery compensates for fluctuations of the ac power source is maintained in a fully charged condition. However, one problem with operation of this energy savings device is that while the power supply is designed to maintain a constant voltage on the load, the power supply also introduces additional power losses. Nor does it cope with the varying demands of ac loads, insofar as efficient supply of energy is concerned.
U.S. Pat. No. 4,206,367 to Petruska, et al. discloses a 220 volt power supply having an internal dc battery and a charge/discharge circuit. The energy savings device operates to reduce the power drawn from the utility company supplied external ac source while servicing the residential load. The device is constructed to provide a continuous sinusoidal wave through opposite phase coupled dc batteries. However, because of the inherent delays in the batteries, only an approximated sinusoidal waveform is achieved which is not sufficient to power the electric motors and power supplies of modern equipment used in residences and businesses.
The Petruska energy savings device is a 220 volt device which is intended to be connected between the utility power metering device and the residential circuit breaker box. A power consumption meter is a 220 volt device which is intended to be connected between the utility power metering device and the Petruska energy savings device. Residential use, while sometimes at 220 volts for appliances such as electric ranges and clothes dryers, is primarily delivered at 110 volts. This is accomplished by splitting a three-wire 220 volt supply line into two, two-wire 110 volt subcircuits in the residential distribution box; i.e., the circuit breaker box.
Use of circuitry such as the Petruska power supply, in cooperation with electrical loads, has resulted in the increased use of power consumption metering of the power supplied by public utilities to their customers. However, these power use meters are often unable to accurately measure energy savings actually being attained. Most (if not all) power consumption meters measure 220 volt current usage across the load to calculate residential power consumption at both 220 volts and 110 volts, often resulting in an error in calculating the true power consumption.
One method of improving the actual, real time measurement of the power consumption is through use of the error compensating circuit described in U.S. Pat. No. 5,319,300 to Wood. Wood discloses an error compensation or correction circuit comprising a pair of capacitors straddling a third capacitor or a rechargeable battery source and uses switching transistors to apply an instantaneous voltage level corresponding to the sinusoidal ac supply voltage by controlling the charging and discharging of the voltage storage elements (i.e. the capacitors and battery). This results in an applied reverse current flow to the power metering device furnished by the power company which corrects the power consumption measurement of the metering devices attached across the electrical load.
Such a residential power consumption meter is connected directly to the utility power metering device and uses the 220 volt power supplied at that point to calculate and record (by magnetic rotating dial and hand pointers) the power consumption of the customer.
The ability of circuits such as the Petruska energy savings device to react to changes in current demand is severely limited by the voltage storage devices' (i.e. the batteries) slow response times. The Wood patent substitutes for these devices voltage storage elements with faster response times (i.e. capacitors) which achieve a significant reduction in response time resulting in a more accurate error compensation for the instantaneous current draw. However, due to the continued use of the complex circuitry arrangement which included, for example, complimentary and opposing current flow compensation circuits, the instantaneous result did not produce the desired pure sinusoidal waveform.
U.S. Pat. No. 5,637,989 to Wood discloses an electrical power energy savings circuit for use with 220 volt ac power delivery systems for reducing the power drain of the power delivery system during the “off phase” for each of the 110 volt legs of the ac power supply circuit as measured across the load. However, this circuit is required to be attached to each 110 volt leg of a 220 volt ac supply line. Additionally, a voltage delay elimination means is required to provide a current demand following device to constantly monitor the load so that the half wave produced from the dc voltage storage device is triggered at the appropriate instant in time. Otherwise, an offset or delay could occur in the sinusoidal waveform applied to the load, damaging ac motors and other similar devices.
In response to these problems, Wood further disclosed in U.S. Pat. No. 6,215,203 a power supply circuit utilizing an ac power source, voltage storage device (capacitor), and switching device (transistor and transformer) to produce a complete sinusoidal waveform instantly to a load. However, the use of these transformers and transistors consumed power that might otherwise have been utilized more efficiently.
Accordingly, there remains a continuing need for a more simplified electrical power energy savings circuit that can utilize the sinusoidal wave form supplied by the power company more efficiently. The present invention fulfills this need, and further provides related advantages.